The article “Medipix2: A 64-k pixel readout chip with 55-μm square elements working in single photon counting mode” by X. Llopart et al., IEEE Transactions on Nuclear Science, volume 49, issue 5, pages 2279 to 2283, October 2002 discloses a photon counting detector, which generates detection values depending on detected photons. In particular, a direct conversion material is used for transforming photons into signal pulses, wherein each signal pulse corresponds to a single photon and wherein the signal pulse height of the respective signal pulse is indicative of the energy of the respective photon. The signal pulses are distributed among several energy bins, wherein for each energy bin a detection value is generated, which is indicative of the rate of signal pulses assigned to the respective energy bin.
The signal pulse height can comprise an offset caused by persistent currents. This offset may lead to a corrupted distribution of the signal pulses among the energy bins and, thus, to a reduced quality of the generated detection values.